Automatic telephone system



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INVENTOR WINFRED T. POWELL BY 4 ATTORNEY w. 'r. POWELL- Au'iomwx-c TELEPHONE SYSTEM Filed Nov. 30, 1921 lvll Jan. 12 1926.

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EOFUMJMD Iut w U13 Patented Jan. 12, 1926.

UNHTEE) starts PATENT oFFicE.

WINFRED '1. POW'ELL, OF ROCHESTER, NEK J YORK, ASSIGNO R'TO THE STROMBERG- CARLSON TELEPHONE MANUFACTUBI A coaronarron or new roan.

Ne COMEANY, or Roonnsrnn, NEW YORK,

AUTOMATIC TELEPHONE SYSTEM.

Application filed November phone systems and more particularly to line indicating devices in such telephone systems. Tn telephone systems employing automatic switches in completing some portion of a telephone connection, it becomes necessary when a calling subscriber desires to obtain a toll connection by directively setting one or more automatic switches to complete a connection with the toll operators position, to

provide some means for indicating the designation of the calling line so that the toll operator can check the number of the calling line as given by this subscriber, in order to correctlytharge for the toll connection.

In accordance with one feature of the present invention'means are provided whereby alternating current is employed to actuate a line indicating device or devices.

In accordance with another feature of this invention means are provided including a rectifying device such as a detector of the thermionic type or of the crystal type for controlling a line indicating device.

The drawings with Fig. 2 placed at the right of Fig. 1 diagrammatically represent portions of a telephone system including the present invention. At the upper left hand corner of Fig. 1 thereis represented the substation circuits and the individual line switch of a telephone line. At the'right of the dotted line in Fig. 1 there are represented the circuits'of a. selector switch which functions to select trunks leading to an idle operators position. At the lower left hand corner of'Fig. 1 there are represented two.

thermionic devices which co-operate in the indication of the number of the calling switch.

At the left of the dotted' linein Fig. 2

there appears a cord circuit and an operators telephone set ofatoll operators position. At the right of the dotted line of Fig. 2 there is indicated-a called telephone. line, and the rectangle including the legend 30; 1921. Se-rial No. 518,874.

To distant ofiice indicates that one or more operators cooperate to telephone connection,

The structure ofthe line switch and the selector are now wel known and it is not necessary todescribe the samei It is only complete the desired necessary to point out that in-a 10,000 line system there will be 200 lamps-such as those designated .54 and 60, which lamps are vis 1ble to a plurality of operators and each lamp such as .54 indicates the thousands and hundreds digit of the calling line, while the lamp such as 60 indicates the'tens and unitsdesignation of the calling-line. I V i It 1s believed that the invention will best be understood by describing the method of extending a callingtelephone line to an idle hook the line relay 5 is energized through a circuit extending from grounded battery, winding of this relay, inner upper back contact and armature of the cut-0E relay 6,

over the lower side of the calling line through the substation circuits at A, over the upper side of the calling line, armature and back. contact of the cut-off relay 6 toground. The line relay 5 is energized .in

this circuit and completes an operatingcircuit for the motormagnet 7 of the line switch individual to the calling line, which circuit is'traceable from grounded battery, primary Winding v73 0f the induction coil, winding of the motor magnet 7 its back contact and armature, lowermost back contact and armature of the cut-off relay 6, test brush 8. of the line switch, conductor 9, front contact and armature of; the line relay to ground. .Under the control of thiscircuit the primary line switch leaves the normal position in which it was'resting and proceeds to: test the terminals such as 10 and 1150f trunk circuits leading to selector switches.

whosetest terminal, Which'is designated 10,

is busy, which condition is indicated by.v the presence of ground potential on the termiground through a primary'winding similar to 1,2 of an r dacti n 00 .1, a conductor 5 mi- Let it be assumed that the trunk circuit nal 10. This busy potential is applied from lar to 13, lowermost front contact and armature of a'cut-ofi relay similar to 6 and a test brush similar to 8 at the line switch which has previously seized the trunk circuit now being tested. The motor magnet 7 will now continue to advance the brushes 8, 1% 18 and 19 of the line switch untilan idle test terminal such as 11 is reached, this idle test terminal 11 is characterized by the absence of gronnd potential, so that the cut-off relay ii which has been shunted during this operation of the motor magnet is now actuated in a circuit traceable from grounded battery, primary winding 73 of the induction coil, windine, hack cohtact and armature of the motor magnet 7, windingof the cut-off relay G holding brush 14, holding; terminal 15, outer armature and back contact of the secondary motor magnet 16, off normal contacts 17 to ground. Themotor magnet is marginal and will not operate in series withthe cut-off relay 6 so that the line switch will be stopped with its brushes in engagement with the trunk circuit shown at the right of 1. As soon as the cut-off relay {5 is operated it e tends the two sides "of the calling line to the brushes 18 and 19 of the line switch through the upper armature and back contact of relay 20,, left hand windingrfof the impulse relay 21 to ground and through the inner upper arn'iature and bacl; contact of relay 20 through the right hand winding of the in'ipulsc relay 21 to grounded bat tery. V 1

As soon as the, impulse relay 21 attracts its armature it clo es an operating circuit for the slow releasing holdin "lay 22 and this last [relay its inne arm a ans a n kl front contact closes a substitutecircuit m- (lependent ot the oil normal contacts 17. T The sulfiscriber at A will no n iperate his dial sender to transmit one, or, more in]- pulses correspondin to the designation of the toll operator. Let it be assumed that the subscriber is instructed to dial Owhich transmits a series of ten impulses to signal the toll operator. In response to each of theseim pulses the impulse relay 21 retracts its armature to close acircuit from ground, its armature and loa-clrcontact, lowermost armature and back contact of relay 20, lower armature and front contact of relay 22, winding of the slow releasing changeover relay 23, winding primary motor m agnet 2% to grenades battery. Inresponse to each of these ten impulses transmitted tothe impulse relay 21, the primary motor magnet 24 will advance the brushes 26 2,7 and 28 of the selector switch to the tenth group of trunks terminating in this switch. At the close of this series of impulses, the impulse relay 1 will hold itsarmature at tracted tor :a relatively long intert alwhicl'i results in the deenergization of the changeture "of the holding relay 22. 111g relay serves to extend the calling line through the brushes 26 and 27 of the selecover relay 23. During the time that the change-over relay 23 is operated, a circuit is closed for energizing the test relay 29, This circuit is closed at the, armatiire and front contact the relay and thetest relay 29 as soon as it is operated, locks itself actuated in a circuit traceable from grounded battery, its winding, front contact and armature, contacts 30, outer back contact and armature of the secondary motor mag;- net 16, inner front contact and armature of relay 22 to ground. 1

lVhen the change-over relay 23 deenerg'izes an operating circuit is closed for the sec ondary motor magnet 16 from grounded battery, its winding back contact and armature, hack contact and armature of relay 28, front contact and armature of the test relay 29 in n'iu'ltiple i'th the locking'circuit of the test relay to ground at the fro-ht contact and armature of the holding relay 22. The sec ondary motor magnet 16 is thus actuated to advance the brushes 26", 27 and 28 into enag ment withthe terminals of the first trunk of the selected group, also the secmany motor magnet when operated interrup ts the locking circuit of the test relay 29. If, however, the first trunk tested by the test brush 28 is busy, a condition indicated by the presence of ground potential on its test terminal, the test relay 29 will, therefore, be held operated and the secondai'y motor magnet 16 will heenergized, to advance the brushes of the selector switch over the terminals of busy trnnks.

Let it be 'assu'niedthat the first idle trunk tested is that indicated at Fig. 2 whichhas no ground potential on its test terminal so that the test relay 29 will (lo-energize and prevent further operation of the secondary motor magnet. Switching relay 20 will then be operated at this time in a circuit which may be traced from grounded battery, winding of this relay, back contact and arl'na ture of the test relay '29, oFf-norn'ial contacts 50 to ground at the front contact and arma- The switch switch and through the back contacts and armatures of relay 32 to ground and to grounded battery, through the winding of the slow releasing relay 83. The slow releasing relay attracts its armatnres and at its left hand armature and front contact closes the holding circlliit for the switching relay 20. At the right hand armature and front contact of relay 33, a circuit is closed for lighting the lamp for indicating to the "operator that a call is awaiting her at tention. i i

As soon as the switching relay 2O attracts its armatures it opens the energizing circuit oi?- the impulse relay 21', which immediately deenergizes and opens the circuit of the holding relay 22but this relay is sluggish and holds its armature operated to maintain a holding circuit for the line switch until the slow releasing relay 33 of Fig. 2 is operated to complete a substitute holding circuit for this switch.

The operator notes that the lamp 34 is lighted, inserts an answering plug 35101 a cord circuit at her position into the jack 36 associated with the lamp 34. Relay 32 will then be operated in a circuit completed from grounded battery, its winding, sleeve contacts 01 the jack and plug, winding of relayf37 to ground. The holding circuit is now extended throughthe front contact of relay to ground through the winding of relay'3fZ, The calling line has thus been extended to the conductors 38 and 39'otthe cord circuit and thence over conductor 38 througl'i winding of the repeating coil to ground and over conductor 39 through the supervisory relay 40 and the winding of the repeating coil'to grounded battery. The supervisory relay attracts its armature and thereby prevents thelighting of the answei ing supervisory lamp 41. As soon as the operator has inserted the plug 35 into'the jack 36 she depresses a listening key the contacts of which are designated 42and 43 to connect her telephone set generally designated 44, to the calling telephone line. The

operator then receives the wanted number from the calling subscriber and also requests the number of the ca'lhnghne.

It nowbecomes necessary to check the number 01'? the calling line to determine the circuit including the two sides. of the calling line and the trunk and cord circuits in series to ground and grounded battery, through the lefthandwindings of the repeating coil. The relay 48 thereupon deenergizes and the source of alternating current is extended in a circuit traceable from ground, secondary winding of the induction coil 49, conductor 50,'uppermost back con tact and armature of relay 22, lower armature and front contact of relay 20, back contact and armatureo't'i'elay 48', through the condenser 51, terminal 11 and brush8 of the line switch, lower armature and front contact of the cut-off relay 6, conductor 13, pri mary winding 12 of the induction coil to ground. Thisalternating current is then re peated to the secondary winding 52 of the induction coil which forms a part of the tuned circuit including a part of the cir-,

cuits of thervacuum tube detector as is well known. This alternating current which is repeated to the tuned circuit and the vacuum tube detector rectifies this current to make therelay 53 responsive thereto. In. the event thatthe rectified currenttransmitted to the relay 53 is not sufficient for its op 1 the lamp 54. This lamp indicates the tliou-v sands and hundreds portion ot' the designation of the calling line.

The operator. thereupon depresses ondary lamp key 55 to close a circuit forthe alternating current from groundthrough the winding of tlieinductionicoil 49, con ductor 5 6, key contacts 55, tlleCOIlClGllSGlg contacts of the listening key 43, sleeve contacts of the plug and of the. jack. 36, front contact and armature ofrelay 32, selectortest brush28, off normal contacts 30,- outer back contact and armature of secondary motor magnet 16, test terminal 15, holdingbrush 14 ofthe primary line switch, winding of the cut-off relay 6, back contact, armature and winding of the motor magnet 7, primary winding 7 3 of the induction coil to grounded battery. This alternating current is repeated through "the, secondary winding 5'7 of the induction coil included in the tuned circuit of the detector generally: designated 58. The detector 58 rectitiesthe alternating current and effects theoperation 01 the relay 59 which in turn lights the lamp 60 which lamp indicates the tens and units designation of the calling substation.

these csq Atternhaving thus determinedthat the I calling subscriber has truthfully given the number of the calling line the. operatorthen proceeds to'complete the call ingthe well known. manner by, insertingthefcalling end i of her cord circuit ,into thejack of the trunk leading to the distant o'fiice through I which the called subscriber may bereached. V The toll operatoiyafter the connection has been completed, makes the charge record oi; v the call for the callin subscriber in accord 3 u h ance with the usual practice.

At thetermination of the call when the calling subscriber replaceshisreceiver on its switch hook, the supervisory relay 40 will release its armature and therebyremove the shunt circuit from the answering supervisory lamp 41, whichi's, therefore, lighted'iir forming the toll operator that "the callis terminated. The operator then removesthe plug 35 from the jacki36 which effects-the release of the relay'32. As soon as relay 32 deenergizes it permits the deg-meigization oil the switching relay 20, whereliipon, a circuit is closed 'for the release magnet extending from grounded battery, right hand winding of this magnet, oil normal contacts 76,'back contact and armature of relay back contacts and a'ri'natures or relays 20 and 9 1 to ground. The release magnetwill thus be operated until the selector switch has been restored to normal at which time the oilnormal contacts 76 are opened. With the magnet- 75 energized a circuit is closed from ground, its armature, front contact and left hand winding, terminal 11 of the line switch, brush 8, lower arinature and back contact of relay Gnow deei'iergized, back contact, armature and winding of the motor magnet 7, primary winding '78 of the induction coil to grounded battery. Under the control of this circuit the motor magnet 7 advances the brushes or the line switch to some one of its sets of normal contacts.

In this description thermionic devices have been employed to detect and amplify a source of current which in turn control the operation of the number checking lamps. it will be understood, however, that any other devices which function in a manner similar to this device may be employed.

'What is claimed is 1. In a telephone system, a plurality of telephone lines, each having a dilterent arbi trary designation, an operators position,

'means for connecting a calling telephone line to said operators position, a line indicating device a source of alternating current associated with said operators position, and means responsive to the same number 0t applications of said source of alternating current in all cases and effective after the initiation of calls on said lines for actuating said indicating device in accordance wit-h the designations of said telephone lines.

2. In a telephone system, a plurality of telephone lines, each having a different arbitrary designation, an operators position, means for connecting calling telephone lines to said operators position, a line indicating device, a source of alternating current associated with said operators position, and means including a current rectifying device responsive to the same number of applications of said alternating current on the initiation of calls overthe calling telephone line for actuating said lines indicating device in accordance with the designations of said calling telephone lines.

3. In a telephone system, a plurality of telephone lines, each having a dill'erent arbitrary designation, an operators position, means forconnectinga calling telephone line to said operators position, a line indicating device at said operators position for ind-ieating the designation of calling telephone lines, and manually controlled means includmg an electron d1scharge devlce invariably operated in the same manner in several cases the case of a plurality of telephone lines for causing the actuation of said line indicating device after the initiation of a call on one of said telephone lines.

5. In a telephone system, a plurality of telephone lines, an operators position, means for connecting a calling telephone line to an operators position, a visual line indicat ing device including electron tubes for indicating two different portions of the designation of a calling line, a source of current, operating circuits for said electron tubes, and manual means for completing said circuits to said source of current. p

6. In a telephone system, a plurality of telephone lines, an operators position, means including non-numerical and numerical switches for extending a calling line to an operators position, a line indicating device for indicating the designation of the calling line, a source of current, means including an electron discharge device for actuating said line indrcatmg device, and means for electrically connecting said source of ourrent and said electron discharging device after the connection of the calling line to said operators position by said nonnumerical and nuinerical switches. a

7. In a telephone system, a plurality of telephone lines, each telephone line having a different arbitrary designation, an operators position, means for connecting a calling telephone line to said operators position, a line indicating device and a source of current at said operators position, electron discharge devices for variably operating said line lndieating device to signalthe designationof: calling telephone lines, and means operable after the extension of a calling line to said operators position for connecting said source of current to said electron discharging device.

In witness whereof, I hereunto subscribe myname thijsQSth day of November A. D. 1921. i i

\VINFRED POWELL. 

